Vehicles such as automobiles have an air conditioner system for cooling a vehicle passenger. The air conditioner includes a compressor unit that is driven by the vehicle motor. The air conditioner drive for the compressor requires a substantial amount of power. There are instances where it is desired to limit the amount of power used to drive the air conditioner compressor, such as to conserve fuel or power. Where the vehicle is being powered by an electric motor, there is a particular need to conserve power being drained from the battery to run the air conditioner. This becomes more acute at higher motor speeds. In order to conserve power, it is desired to drive the air conditioner compressor at a relatively constant speed even though the vehicle's electric motor speed is being varied substantially, such as when accelerating the vehicle, traveling in heavy traffic, etc.